DDx Baker's Cyst Popliteal Anerysm Soft tissue sarcoma Osteosarcoma / Parosteal OS Hemangioma / AVM Note: Always do xray for calcification A Bakers cyst / aneurysm can be calcified posterior Mass posterior knee mass knee differential diagnosis Book traversal links for Mass Behind Knee ‹ Knee Pain Up Painful TKA ›